From 0d30bfd6d4eb9bcddbe25fe956d3f5f812cce187 Mon Sep 17 00:00:00 2001
From: "julian.speith" <julian.speith@mpi-sp.org>
Date: Wed, 8 May 2024 14:36:22 +0200
Subject: [PATCH] added function to get all (used) vertices

---
 .../include/graph_algorithm/netlist_graph.h   |  8 +++
 .../python/python_bindings.cpp                | 23 ++++++++
 plugins/graph_algorithm/src/netlist_graph.cpp | 52 +++++++++++++++++++
 3 files changed, 83 insertions(+)

diff --git a/plugins/graph_algorithm/include/graph_algorithm/netlist_graph.h b/plugins/graph_algorithm/include/graph_algorithm/netlist_graph.h
index eaa5bb58917..7878641fe10 100644
--- a/plugins/graph_algorithm/include/graph_algorithm/netlist_graph.h
+++ b/plugins/graph_algorithm/include/graph_algorithm/netlist_graph.h
@@ -174,6 +174,14 @@ namespace hal
              */
             u32 get_num_edges() const;
 
+            /**
+             * Get the vertices in the netlist graph.
+             * 
+             * @param[in] only_connected - Set `true` to only return vertices connected to at least one edge, `false` otherwise. Defaults to `false`.
+             * @returns A vector of vertices on success, an error otherwise.
+             */
+            Result<std::vector<u32>> get_vertices(bool only_connected = false) const;
+
             /**
              * Get the edges between vertices in the netlist graph.
              * 
diff --git a/plugins/graph_algorithm/python/python_bindings.cpp b/plugins/graph_algorithm/python/python_bindings.cpp
index 57a51634b9a..4bcde4dec51 100644
--- a/plugins/graph_algorithm/python/python_bindings.cpp
+++ b/plugins/graph_algorithm/python/python_bindings.cpp
@@ -292,6 +292,29 @@ namespace hal
             :rtype: int
         )");
 
+        py_netlist_graph.def(
+            "get_vertices",
+            [](const graph_algorithm::NetlistGraph& self, bool only_connected = false) -> std::optional<std::vector<u32>> {
+                auto res = self.get_vertices(only_connected);
+                if (res.is_ok())
+                {
+                    return res.get();
+                }
+                else
+                {
+                    log_error("python_context", "error encountered while getting vertices:\n{}", res.get_error().get());
+                    return std::nullopt;
+                }
+            },
+            py::arg("only_connected") = false,
+            R"(
+            Get the vertices in the netlist graph.
+
+            :param bool only_connected: Set ``True`` to only return vertices connected to at least one edge, ``False`` otherwise. Defaults to ``False``.
+            :returns: A list of vertices on success, ``None`` otherwise.
+            :rtype: list[int] or None
+        )");
+
         py_netlist_graph.def(
             "get_edges",
             [](const graph_algorithm::NetlistGraph& self) -> std::optional<std::vector<std::pair<u32, u32>>> {
diff --git a/plugins/graph_algorithm/src/netlist_graph.cpp b/plugins/graph_algorithm/src/netlist_graph.cpp
index fefd434d9b4..b157f4abf9d 100644
--- a/plugins/graph_algorithm/src/netlist_graph.cpp
+++ b/plugins/graph_algorithm/src/netlist_graph.cpp
@@ -396,6 +396,58 @@ namespace hal
             return igraph_ecount(&m_graph);
         }
 
+        Result<std::vector<u32>> NetlistGraph::get_vertices(bool only_connected) const
+        {
+            u32 num_vertices = igraph_vcount(&m_graph);
+
+            if (!only_connected)
+            {
+                std::vector<u32> vertices(num_vertices);
+                for (u32 i = 0; i < num_vertices; i++)
+                {
+                    vertices[i] = i;
+                }
+                return OK(vertices);
+            }
+            else
+            {
+                std::vector<u32> vertices;
+
+                igraph_vector_int_t degrees;
+                if (auto res = igraph_vector_int_init(&degrees, num_vertices); res != IGRAPH_SUCCESS)
+                {
+                    return ERR(igraph_strerror(res));
+                }
+
+                igraph_vs_t v_sel;
+                if (auto res = igraph_vs_all(&v_sel); res != IGRAPH_SUCCESS)
+                {
+                    igraph_vector_int_destroy(&degrees);
+                    return ERR(igraph_strerror(res));
+                }
+
+                if (auto res = igraph_degree(&m_graph, &degrees, v_sel, IGRAPH_ALL, IGRAPH_LOOPS); res != IGRAPH_SUCCESS)
+                {
+                    igraph_vs_destroy(&v_sel);
+                    igraph_vector_int_destroy(&degrees);
+                    return ERR(igraph_strerror(res));
+                }
+
+                for (u32 i = 0; i < num_vertices; i++)
+                {
+                    if (VECTOR(degrees)[i] != 0)
+                    {
+                        vertices.push_back(i);
+                    }
+                }
+
+                igraph_vector_int_destroy(&degrees);
+                igraph_vs_destroy(&v_sel);
+
+                return OK(vertices);
+            }
+        }
+
         Result<std::vector<std::pair<u32, u32>>> NetlistGraph::get_edges() const
         {
             const u32 ecount = igraph_ecount(&m_graph);